1. Field of the Invention
The present invention relates in general to a fan housing and in particular to a housing of a fan assembly that can be easily and securely mounted on a system frame.
2. Description of the Related Art
A conventional fan is shown in FIG. 1, including a rotor assembly 1, a stator 2 and a frame 3. The rotor assembly 1 includes a blade structure 11 having a hub 111 and blades 112 disposed around the periphery of the hub 111. A metal shield 12 and a magnet 13 are disposed in the hub 111 accordingly. A shaft 113 is placed in the center of the hub 111 and a washer 14 is placed on the shaft 113. The stator 2 includes a sleeve 21, a coil 22, an upper insulation spacer 23, an upper pole plate 24, a lower insulation spacer 25, a lower pole plate 26 and a circuit board 27. The sleeve 21 is a hollow tube and a ball bearing 211 is disposed in the upper interior portion of the sleeve 21. The lower portion of the sleeve 21 has a self-lubricating bearing 212. Several bushings are placed between the ball bearing 211 and the self-lubricating bearing 212. The upper insulation spacer 23 and the upper pole plate 24 are placed sequentially on top of coil 22, and encircle the outer periphery of the sleeve 21. Next, the lower insulation spacer 25, the lower pole plate 26 and the circuit board 27 are placed sequentially and encircle the outer periphery of sleeve 21. Thus, the top surface of the lower insulation spacer 25 contacts the lower end of coil 22. The shaft 113 of the rotor assembly 1 passes through the opening in ball bearing 211 and the self-lubricating bearing 212 and a ring is locked at the end of the shaft 113 to connect the rotor assembly 1 and the stator 2. Further, a sensor is disposed on the circuit board 27 for detecting and controlling the magnetic field of the stator 2. Finally, the bottom surface of the stator 2 is connected to the frame 3 thereby completing the fan assembly.
In practice, the fan is fixed in a system, such as a computer, through the frame 3. Referring to FIG. 2a, a conventional frame 3 has a main body 31 and through holes 33 formed at each corner of the frame 3. Referring to FIG. 2b, the fan is fixed onto the system frame 36 by a screw 37 passing through the through hole 33 and a hole disposed on the system frame 36 to engage with a nut 38. However, such a frame 3 is so thick that the screw 37 must be longer enough to pass therethrough to complete the assembly. Further, as shown in FIG. 2b, the end of the screw 37 protrudes out of the system frame 36, which will easily hurt the assemblers or users. Additionally, when assembling, the fan must be held to fasten the nut 38 for fixing the fan to the system frame 36; accordingly, a large assembly area is required.
Another conventional frame 3′ is shown in FIG. 3a. The frame 3′ has a main body 32 and flanges 34 formed at each corner of the frame 3′. An opening 35 is formed on each flange 34. Referring to FIG. 3b, the fan is connected to a system frame 36 in a system (such as a computer) by a screw 37′ passing through a hole formed on the system frame 36, the opening 35, and a nut 38′. The flanges 34, however, are not completely supported, and the screw 37′ only passes through the opening 35 on one side of the frame 3′ for clipping the flange 34 of the frame 3′, such that the assembling strength is obviously insufficient. Likewise, the fan must be held to fasten the nut 38′, for fixing the fan to the system frame 36; accordingly, ir is relatively inconvenient and a larger assembly area is required.